Pumpkin Agronomy Guide
Description
As a member of the cucurbit family, the pumpkin has features and agronomic requirements comparable to those of other cucurbits, such as cucumbers, watermelons, squash and gourds. Pumpkins prefer 65°F to 95°F temperatures. Given the right conditions, good yields tend to total 15 tons per acre to 25 tons per acre. Because of recurring pest and disease pressures, pumpkins benefit from a three-year rotation with non-cucurbits.
Site Selection
To perform best, pumpkins need full sun. Pumpkins prefer well-drained, neutral or slightly alkaline soils, and in the selected growing areas, the soil pH should be 7.0. Silt loams low in clay fit well with pumpkin production. Adding organic matter can enhance clay-containing soils and improve drainage. For example, incorporating peat, compost or rotted manure may lighten heavy soils. Producers may also consider drainage tiles, raised beds and planting ridges as options to improve soil drainage capabilities.
Sandy soils warm quickly during the spring, so they work well for pumpkin production in northern areas. Although low-lying areas offer fertility and drainage benefits, they have possible disadvantages, including increased foliar disease risk and fall frost susceptibility.
Fertility
To develop, pumpkins need low nitrogen, high potassium and high phosphorous levels. Although pumpkins don’t need high nitrogen levels, nitrogen supplies may drain quickly from light, sandy soils, which may benefit from a 1-tablespoon per hill nitrogen side-dressing (33-0-0) a week after blooming begins and then again three weeks after the first blooms appear. Too much nitrogen, however, stimulates plant growth and limits fruit production, so avoid overapplication. To optimize performance, add 1 tablespoon to 2 tablespoons of complete fertilizer per hill – possible analyses include 4-8-5 or 6-10-10 – before planting.
Variety Selection
To produce uniform-, desirable-looking pumpkins, annually purchase new seed instead of saving seed. Many pumpkin cultivars are hybrids. If varieties cross pollinate, then that may lead to misshaped fruit or fruit with unappealing features. Growers have several possible pumpkin varieties from which to choose.
Recommended Pumpkin Varieties
| Name | Notes |
|---|---|
| Howden Biggie | Connecticut Field type, large |
| Jack-O-Lantern | Good for Halloween |
| Jack-Be-Little | Novelty miniature for decoration |
| Lumina | White with orange flesh |
| Small Sugar | Small pie pumpkin, stores well |
| Spirit | Semibush type, hybrid |
| Oz | Semibush plant, produce 3 pound to 5 pounds fruit |
| Spookie | — |
| Connecticut Field | 15 pounds to 25 pounds fruit |
| Gold Rush | 30 pounds to 40 pounds fruit |
| Howden | 15 pounds to 25 pounds fruit |
| Jackpot | 20 pounds to 25 pounds fruit |
| Mother Lode | 18 pounds to 25 pounds fruit |
| Pankow’s Field | 15 pounds to 20 pounds fruit |
| Wizard | 10 pounds to 15 pounds fruit |
| Pro Gold 500 | 22 pounds to 24 pounds fruit |
Planting
Producers may plant pumpkins after the spring frost risk ends. For fields to be suitable for pumpkin planting, soil temperatures must have elevated to 60°F at a 3-inch depth. At cooler temperatures, seed may rot. When selecting a planting date, be mindful of a variety’s days-to-maturity number and the prime pumpkin marketing window, which tends to be mid-September to Oct. 31. Allow ample time for growing and marketing.
To plant pumpkins, producers may form mounds or hills that are 8 inches to 10 inches high. Elevating the planting area using mounds or hills warms the soil. Within each hill, plant four to six pumpkin seeds in a circle. Target a half-inch to 1-inch planting depth. In Missouri, the recommended minimum row spacing is 48 inches for hand cultivation and 60 inches for field-implement cultivation. Within a row, spacing should be 60 inches between plants. As an alternative to sowing seeds, growers may consider starting pumpkins with transplants.
Cultural Management
Several cultural management strategies influence pumpkin production potential. After seedlings emerge and grow two to three leaves, thin seedlings to two to three plants per hill. Such thinning reduces disease risk and improves yield potential.
Producers may mulch pumpkin fields to suppress weeds and provide other benefits. Black plastic attracts sunlight, increases soil temperature and preserves soil moisture content. Alternatively, producers may apply organic mulch, such as peat moss, compost, untreated grass clippings or weathered straw, at a 3-inch depth after soil temperatures rise. When using organic mulch, supplement nitrogen at 1 tablespoon per bushel of mulch.
To facilitate pollination and boost yield potential, allocate one or two honey bee hives per acre. Pollination is critical during the first three months to four months when vines bloom.
Avoid exposing pumpkins to hard frost conditions, which may soften the fruit. Light frosts may also cause damage, so cover pumpkins even for light frost risks.
Water Management
Pumpkins have deep roots. During the growing season, pumpkins should receive 12 inches to 15 inches of water from rainfall or irrigation. Water is especially crucial when pumpkin vines bloom and begin supporting fruit. As the season progresses, pumpkins need less water as they promote fruit maturation. By later in the season, pumpkins will have expanded root systems and tolerate less moisture.
Although pumpkins don’t require irrigation in most soil types, it helps during dry times. Irrigation has greater importance when growing pumpkins in sandy soils. When selecting an irrigation method, furrow irrigation works best. Soaker hoses are another option. Overhead sprinklers may be used; however, they dampen foliage and may increase disease risk. If irrigating, water slowly each week, and apply 1 inch of water. When watering, allow moisture to penetrate and soak the soil at a 6-inch to 8-inch depth. To avoid leaf diseases from spreading, try to water during the morning or early afternoon.
Weed Control
A well-prepared seedbed provides the first line of weed defense. For weeds that emerge, producers may use hand-weeding or hoeing to manage them until pumpkin vines mature. Shade from the vines will inhibit weed growth and enable pumpkins to compete with weeds.
Several recommended herbicides may manage weeds in pumpkin fields.
- Preplant or preplant incorporated: Prefar
- Preplant or pre-emergence: Gramoxone products
- Pre-emergence: Command, Strategy
- Post-emergence: Aim, Goal/GoalTender Gramoxone products, Poast, Sandea, Select Max
- Post-harvest: Gramoxone products
In no-till pumpkin production systems, growers may plant cereal rye or hairy vetch as cover crops in the fall. During spring, growers may control cover crop growth with herbicide burndown or mowing, and the residue acts as mulch to deter weed growth.
Insects and Diseases
Regular spraying prevents insects and diseases from compromising plant health and yields. When applying insecticides, avoid spraying in the morning or early afternoon when bees actively pollinate. Pests that affect pumpkins include striped and spotted cucumber beetles, squash bugs, squash vine borers, aphids, two-spotted spider mites and seed corn maggot.
Diseases that may influence pumpkins include downy mildew, powdery mildew, fusarium wilt, plectosporium blight and phytophthora blight. The recommended practices – both cultural and chemical – for preventing and controlling these challenges vary by disease. Strategies include rotating with non-susceptible crops, applying fungicides, removing standing water, selecting resistant varieties and managing pests that spread disease.
Harvest and Storage
Harvest requires the most labor investment during the pumpkin production process because producers typically harvest the fruit by hand. Pumpkins with a deep, solid color and hard rind are ready for harvest. As another signal, pumpkin vines typically start dying near harvest time. While removing pumpkins from the vine, leave a 3- to 5-inch stem. Because pumpkin blooming and pollination may not occur evenly during the growing season, harvesting may involve multiple passes through a field at different times.
To extend shelf life, producers may cure pumpkins during a 10- to 20-day period. During curing, pumpkins further ripen, which leads to stronger skins and the fruit healing any wounds. To cure pumpkins, store them in a well-ventilated area – a space that exchanges air about four times per day – with temperatures at 75°F to 85°F and relative humidity at 80 percent to 85 percent. After harvest and the optional curing process, ideal storage conditions are 50°F to 55°F and 50 percent to 70 percent relative humidity. Generally, producers may store pumpkins for two months to three months and maintain fruit quality.
Although not typically recommended, producers may wash pumpkins to remove dirt. If washing pumpkins, use chlorinated water — at least 50 parts per million liquid bleach to 999 parts per million water – and then dry the fruit well. No-till systems may reduce the need for washing because the pumpkins rest on cover crop residues instead of bare ground.
Sources
Bratsch, Anthony. 2009. Specialty Crop Profile: Pumpkins. Virginia Cooperative Extension and Virginia Polytechnic Institute and State University. Blacksburg, VA 24061.
Latin, Richard and Karen Rane. 1999. Identification & Management of Pumpkin Diseases. Purdue University Cooperative Extension Service. West Lafayette, IN 47907.
Lerner, B. Rosie and Michael N. Dana. 2001. Growing Cucumbers, Melons, Squash, Pumpkins and Gourds. Purdue University Cooperative Extension Service. West Lafayette, IN 47907.
Orzolek, Michael D., Timothy E. Elkner, William J. Lamont Jr., Lynn F. Kime and Jayson K. Harper. 2012. Pumpkin Production. Penn State Extension. University Park, PA 16802.
Schultheis, Jonathan R. and Charles W. Averre. 1998. Storing Winter Squash and Pumpkins. North Carolina Cooperative Extension Service. Raleigh, NC 27695.
Snapp, Sieglinde S. and Dale R. Mutch. 2003. Cover Crop Choices for Michigan Vegetables. Michigan State University. East Lansing, MI 48824.
University of Illinois Extension. 2004. Harvesting and Storing of Pumpkins, Winter Squash and Gourds. University of Illinois Extension. Urbana, IL 61801.
University of Missouri Extension. 2000. Vegetable Planting Calendar Pumpkin. University of Missouri Extension. Columbia, MO 65211.
Virginia Cooperative Extension. 2014. Commercial Vegetable Production Recommendations. Virginia Tech and Virginia State University. Blacksburg, VA 24061.